This invention relates to a novel proton permselective solid-state member which is usable in various electrochemical apparatuses such as electric cells like fuel cells and concentration cells, systems for production and refinement of hydrogen under the influence of electric field and hydrogen detectors, for example.
Generally as the electrolytes in fuel cells, there have heretofore been used liquid electrolytes such as potassium hydroxide and phosphoric acid. Because of the use of liquid electrolytes, these conventional fuel cells have entailed inconvenience of handling, leakage of liquid electrolytes and various other disadvantages. To take the place of such liquid electrolytes, there have recently been introduced to the art solid electrolytes such as, for example, an oxide ion conductive solid electrolyte formed of a solid solution of ZrO.sub.2 and CaO. These solid electrolytes can substantially eliminate the disadvantages of said liquid electrolytes. Since they exhibit low levels of ionic conductivity, however, they have to be operated at temperatures in the neighborhood of 1,000.degree. C. As a consequence, the amounts of energy required in operating electric cells utilizing such solid electrolytes are large. This fact directly implies that the devices and parts usable in said cells must be made of materials resistant to heat and corrosion. These solid electrolytes are disadvantageous in this respect. For the materialization of a fuel cell making use of a solid electrolyte, therefore, need is felt acutely for the development of a solid electrolyte which functions effectively at temperatures below 700.degree. C.
An object of the present invention is to provide a proton permselective solid state member capable of exhihibiting an excellent ionic conductivity at temperatures around room temperatures up to a few hundred degrees centigrade.